High-Resolution LC-MS Characterization of Ramaria flavobrunnescens, a Coral Mushroom Toxic to Livestock, Reveals Fungal, Bacterial, and Eucalyptus Tree Metabolites

Ramaria flavobrunnescens is an ectomycorrhizal coral mushroom that is often found growing in eucalyptus forests. The mushroom has been linked to accidental ingestion-associated livestock poisonings in South America, though the toxicological agent has not yet been described. Mushroom samples identified as R. flavobrunnescens were analyzed by liquid chromatography high-resolution mass spectrometry (LC-MS/MS) to determine the potential source of the toxicity, and to provide a metabolomic profile of the species. Previously reported Ramaria secondary metabolites were detected, including ramarins, ramariolides, pistillarin and arsenic-containing compounds. A number of Bacterial species were isolated from R. flavobrunnescens that produced iron-chelating cyclic peptides, which were detected in the mushroom samples. Interestingly, we detected a series of eucalyptus tree secondary metabolites in abundance from R. flavobrunnescens fruiting bodies, some of which have reported toxicities and bioactivities. To our knowledge, this is the first report of eucalyptus secondary metabolites in a mushroom. The diversity of secondary metabolites identified in the mushroom extracts provides insight into the potential complex ecological interactions between R. flavobrunnescens, its associated microbiota, and its mycorrhizal interaction with eucalyptus trees.

Ramaria mushroom poisoning; high-resolution mass spectrometry; mushroom endophytes; mycorrhizal symbiosis.